To me it sounds like he is scared during the pick up and eager to get to his cage when you put him down. Might as well be frustration, if he doesn't want to be out of the cage.
Does he pull on your clothes during the transportation as well?
I think you can give him a threat when you are handling him to keep him occupied or when he is at your lap, so he kinda connects the whole experience with something positive. I do that, but not every time.
Also if there is a time when he doesn't pull at your clothes as normal, you can give him a threat then as well, kinda like positive reinforcement and the stroke near the eyes. I did that when Mylo wasn't lunging at my hands. It was impossible for me to lift his head when he was like that as he was getting stressed out and more aggravated and I was scared that he might bite deep. He is a lot better with this now and he is easier to groom and to do health checks out of my two piggies.
There might many reasons why he does that, I gave you some ideas, but you as the owner are the one who is the most in tune with him and has to figure it out. Each piggy has it's own quirks as well.
If you think he doesn't want to be held at that time then respect that and leave it for later.
If you think it's because he is scared/uncomfortable than try to hold him in a different way or use something to transport him- cuddle cup, blanket, etc..., give him treats and lots of patience.
How To Pick Up And Weigh Your Guinea Pigs Safely (videos)
If you think it's something more of a habit than the Piggy whispering tactics might work better.
You get the gist of it.
But if he is doing that to display discomfort/stress I wouldn't want him to stop until the problem is resolved.
From what I have read many piggies do this, some even say they might do it as a sign of affection to groom you. It depends on the specific situation.
I feel you. My Mylo did a 180 in terms of his behaviour right after that vet visit, when I tried to take him out of his career.
In a previous post you said you think it is rebellion, may I ask why you think that?
Also it might be something that he will keep on doing and you need to find a way to not let him near your clothes, rather than changing his behaviour. Would be easier and quicker.
I was only kidding when I said rebellion , he's coming on for two so I was thinking of toddler behavior. I wrapped him in a towel when I got him out today and he was fine , no pulling. When I picked him up.withoit the towel I held him a bit tighter and he seemed to look more secure. Maybe I've been picking him up.too loosely / casually
I think that guinea pigs out of all pets are the most similar to babies/toddlers in terms of their behaviour and the way we take care of them.
good that he is in better hands now, with someone that cares deeply for him.
